An image heating device includes a tubular film, a heater in contact with an inner surface of the film, and a roller forming a nip part together with the heater through the film. When an image forming apparatus having the image heating device is used to continuously print on small-sized sheets, a phenomenon may occur that the temperature of a region through which paper does not pass in a longitudinal direction in the nip part gradually increases (rise of temperature in a non-paper-passing part). An excessively increased temperature of the non-paper-passing part may damage parts within the device. In a case where printing is performed on larger-sized paper when rise of temperature in the non-paper-passing part occurs, hot offset of toner may be caused on a film in a region corresponding to a non-paper-passing part for small-sized paper.
One of schemes for suppressing such a rise of temperature in a non-paper-passing part, an apparatus has been proposed which includes a plurality of groups (heating blocks) of longitudinal heating resisters in a heater, wherein the heating distribution of the heater is changed in accordance with the size of a recording material (PLT1).